//https://leetcode.cn/problems/sqrtx/
class Solution {
public:
    int mySqrt(int x) {
        if (x == 0)
            return 0;
        int left = 1, right = x;
        while (left < right) {
            long long mid = left + (right - left + 1) / 2;
            if (mid * mid <= x)
                left = mid;
            else
                right = mid - 1;
        }
        return left;
    }
};